Many of the drugs used for chemotherapy in human medicine have central nervous system activity. The mechanisms of action for the primary effects are in most cases poorly understood, while those of the associated minor effects often have not been studied. Three classes of chemicals which are used often by people over the world and which cause increased hunger are: barbiturates (sedatives), benzodiazepines (minor tranquilizers), and cannabinols, e.g., marihauna, tetrahydrocannabinol (psychotomimetics). In previous work, we have used an animal model in which all these chemicals are effective in eliciting feeding by oral and/or intravenous administration, and we propose to determine if a representative of each class will cause feeding by acting on the hypothalamus. Ventromedial (inhibiting) and lateral (exciting) hypothalamic areas are especially important in the control of feeding behavior. In our experiments, each of the three chemicals will be tested, by intrahypothalamic injections, for a direct dose-related effect on these two areas as measured by the effect on feeding and associated behaviors. Although all the chemicals cause feeding, it is predicted that the mechanism of action will differ, e.g., cannabinols will act on the lateral area while barbiturates will act on the ventromedial area.